In hog rearing operations, it has become essential to maximize the reproductive capacity of the sows. Originally, many hog raising operations simply relied on letting nature take its course with impregnation of the sow by the male hog. However, with larger operations, it became necessary to increase the reliability and accordingly, artificial insemination has been widely practised.
In order for artificial insemination to work efficiently and economically, it is necessary to administer the semen at the time when estrus is occurring. Typically, semen is administered between 1 and 4 times during estrus in predetermined spaced apart time intervals.
It has been proposed in the art to use instrumentation to attempt to determine estrus. Typically, there have been proposed various types of temperature sensors and probes insertable into the vaginal canal for detecting either an increase in temperature or increase in current flow through the mucous. Although these methods do work, they are both time and labour intensive and increase the risk of mortality through contamination, infection, etc.
More traditionally, the techniques employed on the modem day farm is to circulate a male hog down a row of cages containing the sows.
Despite all the advances in the art, typically the impregnation success ratio (i.e. the number of sows successfully impregnated) is in the area of between 75% to 85%. While these rates represent a vast improvement over older success rates, it is obviously desirable to further increase the rate.